Light control system



June 30, 1931. R. H. RANGER LIGHT CONTROL SYSTEM Filed Oct. 31, 1928INVENTOR RH RANGER I BY} 4 2/ 4% A RNEY 310mm) HowLAnn RANGE-E, orNEWARK, new

1 my present invention.

Patented June 30, 1931 UNITED STATES- PORATION OE AMERICA,

PA rear crates LIGHT oonrnon SYSTEM Application filed October 3 1, 1928.Serial No.'316,157.

The present invention relates to a method and means for controllinglight and is especially adapted to the transmission of pictures and thelike for facsimile and television work. By the term pictures, of course,I mean the transmission of views printed matter,"checks, finger prints,photographs,

motion picture film with or without sound' accompaniment, and the like,and, in fact, all types of communication wherein a visual or soundrepresentation of the subject mat ter transmitted is reproduced at areceiving point. a

In the prior art, so far as I am aware, it has been customary to chopthe light from a. picture which is to be transmitted prior to the timethat the light from the picture reaches the photo cell. It has beencustomary, in arrangements of this type, as is readily shown by theprior art, to produce this chopping action by means of rotating disksand the like which are provided with a series of holes through which thelight may pass and, also, by means of disks provided by slots throughwhich the light may pass. According to these arrangements of the priorart it will be seen that there are certain objectionable featuresoccasioned, in that half of the light from the light source is lost orthrown away and is unusable.

vention to provide a means whereby the objectionable features of losingor. throwing half the light away may be avoided and in order toaccomplish this end I have found that the utilization of the deflectionof light is suitable. In accordance with, the utilization of thedeflection principle I may utilize the light source for substantiallythe total amount of the time of transmission and in so doingconsiderably increase the efficiency of the transmitting system.

Other objects and advantages of the pres ent arrangement will at once beapparent from a consideration of the following specification and claimswhen read in connection with the accompanying drawings whereinthevarious figures thereof represent in a convention manner, theprinciple covered by Fig. 1 illustrates an arrangement wherein a. tuningfork provided with a reflecting surface is utilized for alternatelydirecting the lightbeams in a pair of paths at a rate corresponding to,the vibration period of the fork and further illustrates an amplifyingscheme for amplifying electrical currents produced through the action ofreaching each of a plurality of photowcells.

Fig. 2 conventionally.illustrates amodific'ation of Fig. 1 wherein adisk with pris matic lenses mounted thereon is provided light beams forcontrollingthe direction. of the light; I

and

3 represents still a further modification'wherein I have utilized a diskprovided.

with a series of mirrors for deflecting and controllingthe light beamsand'switching from one to another of thephoto cells. In. each of Figs. 2and 3 the system of amplifying the photoelectric currents is notillustrated since it is to be understood that this may be substantiallya duplicate of that shown by Fig. 1. I I

N ow making reference to the accompany ing' drawings, and particularlyto Fig. 1 thereof, a tuning fork or other appropriate vibratinginstrumentality 1 may be driven electrically by means of the windingsfiand I 5 energized from any suitable source 7. On It is, therefore, an obect of my present one of the tines ofthe fork I may supply a wedgeshaped member, generally designated angular reflecting .annsnv,'Assrenoa To RADIO coae coBroRArIon' cannnawenn As shown by Fig. 1 thesurfaces 11 and 13 may be silvered, or they may behighly polished metal.While I have above stated that the tuning fork is to be drivenelectrically it is also within the scope of thatthe forkmay be driven byan air drive means, for example, a-drive of the character disclosed inmy copending application Serial Nof169,620, filed February 19, 1927,and,

also, that the fork may be driven from a master oscillator of anysuitable type] In connection with the transmission of facsimiles motionpicture films, and the like, the record 19 to.

this invention be transmitted maybe in the form of a continuously movingfilm, or, of a picture negative wrapped around a drum for transmission,or, may be of any other character, such as, a completed pic ture ornewspaper clipping, or the like, from which light is either reflected orpassed directly through. In the present disclosure I have, however,illustrated a system wherein light issuing from a source 21 is directedby means of a lens 23 so as to pass throu h the negative (or positive,if desired) to e transmit-ted, assuming that the scheme is one adaptedfor this type of transmission. In this case it is, of course, apparentthat the light from the source which is permitted to pass through thenegative (or positive) varies in direct proportion to the varyingintensities of light and shade making up the picture surface. I have soarranged the point where the light from the source 21 passes through thenegative being transmitted that this point will come at the focus of thelight beams issuing from the lens 23 toward the picture surface. Lightpassing beyond the picture surface 19, and governed in intensity inaccordance with the intensity of light and shade in the picture surface,is directed to a second lens member 25 which is of the condensing typeand which has its focus point arranged at the point Where the reflectedsurface 11 and 13 of the wedge member 9 meet each other.

From the above, it is seen that with tuning fork 1 in a position of restthe light issuing from the optical system 17 comprising the source 21and the lenses 23 and 25 will not be deflected in either direction sinceit will issue as a point source and be protected against the point 15.However, with the fork 1 being vibrated in any desired manner it is atonce apparent that with the tine carrying the vibrating wedge swung to aposition so that the light from the source 21 which passes beyond thepicture surface focused upon the reflecting surface 11, the light beamswill be reflected in a path, designated as A, and by means of the lensmember 27 may then be directly applied to a photo cell 29 forming aportion of an amplifying system for photoelectric currents produced fromthe cell 29 in accordance with the light beams passing beyond thepicture surface 19. In a similar manner it is apparent that with thevarying tine carrying the wedge member 9 being vibrated to its oppositeposition light will be directed to the reflecting surface 13 and willthen follow a path, designated as B, and by means of the lens 31 will beimpressed upon the photo cell 33 in a similar manner to the lightfollowing path A being impressed upon the cell 29.

From the above it is apparent that the light issuing from the source 21and passing 3 through the picture surface will be broken up by means ofthe vibrating wedge 9 attached to the tuning fork 1 in such a mannerthat the output from the two photo cells 29 and 33 will be of the samefrequency as that which has been chosen for the fork and, at the sametime, will provide a means wherein the total amount of light from thesource 21 which is capable of passing through the picture surface 19, inaccordance with the intensity of light and shade'the're-' of, will bebroken up in such a manner that he full benefit of the light isobtained.

The output of the photo cells 29 and 33 may be amplified in the usualmanner and I have herein disclosed a scheme which is a substantialduplicate of that disclosed for a single photo cell by Nicolson Patent,

1,470,696, and includes the potential source 35, 37 connected in serieswith the cells 29 and 33 respectively and each associated with aresistor 39 and 41 connected across the input circuit of a vacuum tubeamplifier 43 and and in series with thephoto cells. It is thus seen thatwhen light is applied to the photo cells a voltage drop occurs in theresistors 39 or 41 and controls the potentials of the control electrodesor grids 47 and 419 of the amplifiers 13 or respectively. Under theseconditions more or less current will flow in the output circuit of theamplifiers 13 or 45 depending upon the amount of light impressed uponthe photo cells associated with each of these amplifiers. The outputcircuit of each of these amplifiers 13 and 15 includes transformercouplings 51 and 53, having their primary windings 55 and 57 connectedwith the output circuit of the amplifiers 43 and 45 respectively. Thesecondary circuit of the transformers 51 and 53 is a secondary winding59 and 61respectively which have one terminal in common and the otherterminal connected to the grid or control electrode 63 and 65 of theamplifiers 67 and 69. These amplifiers 67 and 69 are connected inpush-pull fashion and have the biasing battery 71 for controlling thepotential of the grid members 63 and 65 and a common source, of platepotential 73. The output circuit of the'tubes 67 and 69 is arranged toform the primary Winding 7 5 of atransformer 77 whose secondary member79 is connected with a transmitter in any desired manner. Thetransmitter forms no essential part of my inventlon only in so far as itadds to the combination of the elements herein above set forth and Ihave,

therefore, not attempted to illustrate any particular type thereof.

Now referring to Fig. 2 of the drawings, a rotary disk 81 provided witha plurality of small glass wedges 83 for bending the light rays issuingin a manner similar to that in Fig. 1 from the picturesurface has beenillustrated. It is seen from the showing of Fig' 2 that the light is"alternately switched from photo cell29 to 33'and back again in a mannerquite similar to that shown by Fig. 1. i

Fig. 3 shows still a further modification of the system above describedandparticue larly a modification of Fig. 2 thereof, where- 1n, a similardisk 81 is. provided with a plurality of veins. of reflecting material85 for controlling the light beam. In one position as shown'the lightfrom the'source or the picture surface corresponding to that of Fig. 1is directed straight thr'ough to a photo cell 29 but upon rotation ofthe disk in the directions shown by the arrow light is bent by thereflecting surface from the path by which it would reach cell 29 and isdirected toward cell 33.

The above disclosed invention is also es pecially adopted to multiplexoperation and in this connection there may be a plurality of signallingchannels of the character above illustrated and a plurality ofcontrolling forks or other suitable vibrators to which wedges of asimilar character to the wedge 9 are attached. However, for multiplexoperation it is obvious that it will be desirable to use forks ofdifferent frequency or pitch for each separate signal channelv and tocontrol all forks from a single master oscillator of any desiredcharacter.

While I have above illustrated the above invention in only one of itspreferred forms, it is obvious that I may make such modificationsthrerein as would readily suggest themselves to a person skilled in theart to which the invention relates and I, therefore, do not wish myinvention to be especially limited to the apparatus disclosed butbelieve that I may make such modifications as fall fairly within itsspirit and scope as defined in the following claims.

I claim:

1. In a picture transmitting system, a picture to be transmitted, alight source for directing light to said picture, means for directingthe light issuing beyond said picture along a predetermined path, aplurality of photoelectric elements for translating light energy intoelectrical energy, an amplifying means associated with each of saidphotoelectric elements, and means for continuously shifting the saidlight to switch the light issuing from said picture from one to anotherof said elements and utilizing substantially the entire amount of lightavailable.

2. In a facsimile system, a picture to be transmitted, a light sourcefor directing light upon said picture, means for directing the lightpassing beyond said picture along a predetermined path, means forchopping the light issuing along said path from said picture, aplurality of means for translating the light energy issuing from saidsource 1 and varied in intensity by varying intensities of light andshadow of elemental areas of said picture into electrical energy, and

means for causing the chopped light to alternately influence each ofthelight translating means so as to utilize substantially the full amountof said light.

3. In a facsimile system, a picture to be transmitted, a light sourcefor directing light upon the picture surface and redirecting the i httherefrom alonga predetermined path,

a plurality of photo cells for changing varying light intensities intoelectrical current variations, and means for continually switching thelight beam from one to another of said photo cells sequentially at apredetermined rate whereby substantially the full amount of lightissuing fromthe light source is available for actuating the photo cells.i

4. In a picture transmission system, the combination of a pair ofphotoelectric elements for converting varying intensities of light andshadow on elemental areas of a record surface into varying strengthelectric current impulses, means for directing a beam of light varied inintensity in accordance with the varying intensities; of elemental areasof the record surface along a predetermined path and means foralternately supplying and interrupting the light sup ply to each of thesaid photoelectric ele;-.

ments for producing a light chopping action so as to share the lightbetween the photoelectric elements and utilize substantially the entireamount of light available for conversion into electric currentimpu'lses.

5. Ina facsimile system, the combination of a pair of photoelectricelements for con verting varying-light intensities into vary ingelectric current intensities, means for directing light of an intensitycorresponding to the intensity oflight and shadow of elemental pictureareas along a predetermined its ins

path and a-vibratory light chopping means for alternately subjectingsaid photoeleclJI'lC DIQiIIlS to varying intensities of light wherebythe photoelectric means are successively energized and substantially theentire amount of availabe light is utilized.

6. In a picture transmitting system, the combination of a pairof'photoelectric elements adapted to convert varying intensities oflight and shadow corresponding to elemental areas of a transmittedpicture into,

electric current impulses, means for projectinglight issuing from asource and varied in its intensity by the picture subject along apredetermined path toward said photoelectric elements, and a vibratorylight chopping means in the said light path for alternately subjectingthe said photoelectric elements to the influence of said picturemodulated light so as to utilize substantially the entire amount oflight available in the conpulses.

7 In a picture transmission system, apair of photoelectric elements forconverting varying intensities of light and shadow on elemental areas ofa picture surface into varying strength electric current impulses, apair of push-pull connected amplifiers coupled with the output of saidphotoelectric elements for amplifying currents resulting therefrom uponthe application of light thereto, and a vibratory light chopping elementfor continually switching the light beams from one to the other of saidphotoelectric elements so as to utilize substantially the entire amountof light issuing from the light source for actuating the photoelectricelements.

8. In a picture transmission system, a pair of photoelectric elementsfor converting varying intensities of light and shadow on elementalareas of a picture surface into varying strength electric currentimpulses, a pair of push-pull connected amplifiers coupled with theoutput of said photoelectric elements for amplifying currents resultingtherefrom upon the application of light thereto, and a vibratoryreflecting surface for continually switching the light beams from one tothe other of said photoelectric elements so as to utilize substantiallythe entire amount of light issuing from the light source foractuatingthe photoelectric elements 9. In a picture transmission system,a pair of photoelectric elements for converting varying intensities oflight and shadow on elemental areas of a picture surface into varyingstrength electric current impulses, a pair of push-pull connectedamplifiers coupled with the output of said photoelectric elements foramplifying currents resulting therefrom upon the application of lightthereto, and a tuning fork provided with a wedge-shaped reflectingsurface atthe end of one tine thereof for continually switching thelight beams from one to the other of said photoelectric elements so asto utilize substantially the entire amount of light issuing from thelight source for actuating the photoelectric elements.

10. In a picture transmission system, a pair of photoelectric elementsfor converting varying intensities of light and shadow on elementalareas of a picture surface into varying strength electric currentimpulses,

and a tuning forl; provided with a wedge shaped reflecting surface atthe end of one tine thereof for continually switching the light beamsfrom one to the other of said photoelectric elements so as to utilizesubstantially the entire amount of light issuing from the light sourcefor actuating the photoelectric elements.

11. A picture transmission system com- V in CERTIFICATE OF CORRECTION.

Patent No. 1,811,895. Granted June 30, 1931, to

RICHARD HOWLAND RANGER.

It is hereby certified that error appears in the printed specificationof the above numbered patent requiring correction as follows: Page 3,lines 38 and 39, for "especially" read specifically; same page, line109, claim 5, after the word "means" insert the words in the path ofsaid picture controlled light; and that the said Letters Patent shouldbe read with these corrections therein that the same may conform to therecord of the case in the Patent Office.

Signed and sealed this 3rd day of May, A. D. 1932.

M. J. Moore, (Seal) Acting Commissioner of Patents.

